Asphere of uniform density with mass 21 kg and radius 0.8 m is spinning, making one complete revolution every 0.8 s. the center of mass of the sphere has a speed of 8 m/s. (a) what is the rotational kinetic energy of the sphere?

During the experiment if you could triple the breakaway magnetic force with all other quantities left unchanged, what is the new value for the critical velocity if it was v0 (initial velocity), initially? (b) now if you halved the radius with all other quantities left unchanged, what is the new critical velocity if it was v0 (initial velocity), initially? (c) if during the experiment, critical velocity quadrupled with all other quantities left unchanged, what is the new breakaway force if its magnitude was initially f0,?